AIS - Panacea or Pandora's Box

Wednesday, June 04, 2003

According to Greek legend, Zeus had the messenger god Mercury leave a mysterious box with Pandora. Mercury told Pandora to hold the box for safe-keeping, but under no circumstances was she to open it. Not long after Mercury departed, curiosity got the better of Pandora and she opened the box to examine its contents. Unfortunately, the box contained all the ills and misfortunes of the world. They promptly escaped and have been loose in the world since that time.

The word 'panacea' is derived from the Greek terms "pan" (meaning all) and "akos" (meaning remedy). According to the Merriam-Webster Dictionary, the word means "a remedy for all ills or difficulties."

The question is which term applies to AIS?

What is AIS?

AIS is an electronic transceiver unit intended to be integrated with a ship's radar, gyrocompass, global positioning system (GPS), and other operational and navigational systems. When fully operational and when functioning properly, it will provide the officer in charge of the navigational watch with a radar display that includes a mark for every significant ship within radio range, each with a velocity vector indicating speed and heading. Each ship 'mark' could reflect the actual size of the ship and its position with GPS or differential GPS accuracy. By clicking on a ship mark, the officer could learn the ship name, course, speed, classification, call sign, registration number and other information. Maneuvering information, closest point of approach (CPA), time to closest point of approach (TCPA), and other navigation information could also be available.

AIS operates in the VHF maritime radio band. It is capable of handling more than 4,500 reports / min., and updates itself as often as every two seconds. It uses Self-Organizing Time Division Multiple Access (SOTDMA) technology.

Each AIS system consists of one VHF transmitter, two VHF SOTDMA receivers, one VHF digital selective calling (DSC) receiver, and a standard marine electronic communications link to the shipboard display and sensor systems. Position and timing information is normally derived from a GPS receiver and generally includes a medium frequency differential GPS receiver. Other information broadcast by the AIS is obtained electronically from shipboard equipment through standard marine data connections. Heading information and course, and speed over ground would be provided by all AIS-equipped ships. Other information, such as rate of turn, angle of heel, pitch and roll, destination, and ETA, could also be provided.

The AIS transponder works in an autonomous and continuous mode, regardless of whether the ship is on the high seas or in pilotage waters. System coverage range is similar to other VHF applications. Propagation is slightly better than that of radar due to the longer wavelength of AIS. Thus, it is possible to obtain an AIS report before the true radar image appears on the radar screen. The usual range of AIS is 20 n.m.

The shipboard AIS unit broadcasts the following information every two to 10 seconds while underway and every three minutes while at anchor:

• The unit's maritime mobile identity (MMSI), a unique identifier for each ship radio unit, assigned by the International Telecommunications Union (ITU).

• The navigation status of the ship (e.g., underway using engine, at anchor, not under command).

• Rate of turn.

• Speed over ground.

• Position accuracy.

• Longitude and latitude.

• Course over ground.

• True heading.

• Time stamp.

In addition, the AIS unit broadcasts the following information every six minutes:

• MMSI number.

• Ship's IMO number.

• Ship's radio call sign.

• Name of ship (up to 20 characters).

• Type of ship and cargo.

• Dimensions of ship (in meters).

• Location on ship where the reference point for position reports is located.

The U.S. Federal Communications Commission (FCC) has developed informal guidance regarding approval of AIS installations on U.S.-flag ships, but it has not yet promulgated its regulations. Likewise, the U.S. Coast Guard has issued informal guidance describing the certification process for AIS and other navigation equipment mandated by the SOLAS Convention. Until those two agencies promulgate their regulations, AIS approval for U.S. ships will remain an ad hoc process. Type approvals have recently been issued, though, by the FCC and the Coast Guard for two commercial AIS systems.

Deadlines

There are at least four separate sets of deadlines for use of AIS.

• For ships entering the St. Lawrence Seaway in North America, use of AIS was required as of the commencement of the 2003 navigation season, March 31, 2003. Portable AIS units are available for rent by ships not having AIS permanently installed.

• For ships transiting the Panama Canal, use of AIS will be required as of July 1, 2003. As with the St. Lawrence Seaway, portable AIS units will be available for rent by ships not having AIS permanently installed.

• For ships operating in U.S. waters, installation and use of AIS will be required in accordance with the following schedule:

1. On and after January 1, 2003 for any vessel built on or after that date;

2. On and after July 1, 2003 for any vessel built before January 1, 2003 that is a passenger vessel required to carry a SOLAS certificate, a tanker, or a towing vessel engaged in moving a tank vessel; and

3. On and after December 31, 2004 for all other vessels built before January 1, 2003.

For ships subject to the SOLAS Convention of 300 gt and upwards engaged on international voyages, and cargo ships of 500 gt and upwards not engaged on international voyages and passenger ships irrespective of size, installation and use of AIS is required in accordance with the following schedule:

1. Ships constructed on or after July 1, 2002;

2. Ships engaged on international voyages constructed before July 1, 2002:

a.In the case of passenger ships, not later than 1 July 2003;

b.In the case of tankers, not later than the first survey for safety equipment on or after July 1, 2003;

c.In the case of ships, other than passenger ships and tankers, of 50,000 gross tonnage and upwards, not later than July 1, 2004;

d.In the case of ships, other than passenger ships and tankers, of 300 gt and upwards but less than 50,000 gt, not later than the first safety equipment survey after July 1, 2004 or by December 31, 2004, whichever occurs earlier;

3. Ships not engaged on international voyages constructed before July 1, 2002, not later than July 1, 2008.

Concerns Regarding AIS

Problems have been observed with regard to AIS installations to date. Ship's static data sometimes is loaded incorrectly or not present at all. For instance, ships have reported dimensions via AIS that are obviously incorrect. Some ships are not transmitting heading information via AIS, possibly because the connection of the ship's gyro compass has not been properly made. On some ships, although the AIS system seems to be connected to the gyro compass, the heading information being reported by AIS is different than the actual heading. Some shipborne AIS equipment does not respond to shore station commands. The cause is probably outdated firmware. These early implementation problems highlight the fact that AIS is a complex piece of equipment that only works properly when it is fully integrated into a sophisticated navigational system.

A note of caution is in order. Implementation of AIS has been advanced because of the inherent maritime security aspects of the system. After all, if the authorities ashore can automatically identify ships as they arrive offshore, it makes the job of evaluating risks and allocating scare resources that much easier. On the other hand, as noted above, incorrect (or false) data can be accidentally (or intentionally) programmed into the AIS as currently configured. This would defeat the security purpose of AIS, leading to potentially catastrophic consequences. Further, terrorists, pirates, and others of malicious intent can monitor AIS signals to identify target vessels.

Returning to the original purpose of AIS, maritime safety, all parties should remember the consequences of over-reliance on machines that seem to provide all the answers. One need only look back to the grounding of the cruise ship Royal Majesty on June 10, 1995. The ship was completing a voyage from Bermuda to Boston when it ran aground on the Rose and Crown Shoal about 10 miles east of Nantucket Island, Mass. The ship was 17 miles off course when the incident occurred. Damage to the ship and lost revenue were estimated at $7 million. Subsequent investigation revealed that the ship's automated navigation system had been programmed to rely on its GPS receiver. However, less than one hour after departing Bermuda, the GPS antenna came loose, disabling the GPS. The integrated navigation system automatically defaulted to its dead reckoning navigation system, which does not compensate for the effects of wind, current, or sea conditions. The audible warning system had been disabled and the warning light was displayed only in the chart room. No one on the bridge during the 34 hours between the loss of the GPS signal and the grounding noticed that the ship was off course. None of the other available navigational tools were utilized. The incident provides a valuable lesson in what can happen when reliance is placed in any one system to the exclusion of other systems, including common sense.

Summary

The answer to our original question is that AIS is neither a panacea nor a Pandora's box. It is just another tool in a large and growing tool box made available to masters, deck officers, and others to enhance maritime safety and security. It is only as good as its maintenance and the training provided to its users.